Insufferable: having or showing unbearable arrogance or conceit.
“An insufferable bully.”
“His win made him insufferable.”
Synonyms: conceited, arrogant, boastful, cocky, cocksure, full of oneself, self-important, swaggering; vain, puffed up, self-satisfied, self-congratulatory, smug.
Informal: big-headed, too big for one’s britches, too big for one’s boots.
Being insufferable is a bad thing. It’s generally indicative of Narcissistic Personality Disorder. Yes, some people will like you, but so many more will hate you and anyway, there is no good reason to act this way in the first place. It is absolutely pathological behavior. The insufferable person/narcissist is completely selfish. It’s all about them, all the time. The Me Show is on all day, every day and that’s the only channel. Some of them can be giving, especially to their families, but more often than not you will find that these people cannot be called giving in any way. You’re either giving or taking in life, as life is reciprocal. The insufferable person/narcissist is a taker, not a giver. He takes from most people and gives little if anything in return. Somehow he thinks this is a perfectly fine way to walk through life.